问题描述

Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings.

Machine 1 (sender) has the function:
string encode(vector<string> strs) { // ... your code return encoded_string; }
Machine 2 (receiver) has the function:
vector<string> decode(string s) { //... your code return strs; }

So Machine 1 does:
string encoded_string = encode(strs);
and Machine 2 does:
vector<string> strs2 = decode(encoded_string);
strs2 in Machine 2 should be the same as strs in Machine 1.

Implement the encode and decode methods.

Note: The string may contain any possible characters out of 256 valid ascii characters. Your algorithm should be generalized enough to work on any possible characters. Do not use class member/global/static variables to store states. Your encode and decode algorithms should be stateless. Do not rely on any library method such as eval or serialize methods. You should implement your own encode/decode algorithm.

解决方法

#include <iostream>

string encode(vector<string>& strs) {
    string res;
    for (auto it = strs.begin(); it != strs.end(); ++it) {
        res += to_string(it->size()) + "#";
        res += *it;
    }
    return res;
}

vector<string> decode(string& s) {
    vector<string> res;
    int index = 0;
    while (index < s.size()) {
        int len_end = s.find_first_of("#", index);
        string len_str = s.substr(index, len_end-index);
        int len = atoi(len_str.c_str());
        string str = s.substr(len_end+1, len);
        res.push_back(str);
        index = len_end + 1 + len;
    }
    return res;
}

template<class T>
void print(vector<T>& v) {
    for (auto it = v.begin(); it != v.end(); ++it) {
        cout << *it << endl;
    }
}

int main() {
    std::cout << "Hello World!\n";
    vector<string> raw = {"aaa", "bbbb", "ccccc"};
    string encode_str = encode(raw);
    std::cout << encode_str << endl;
    vector<string> v = decode(encode_str);
    print(v);
}

输出

3#aaa4#bbbb5#ccccc
aaa
bbbb
ccccc